Manufacture of metallic receptacles



Dec. 24, 1940. H. w. CLARK MANUFACTURE OF METALLIC RECEPTACLES Original Filed NOV. 7, 1935 WK M Patented Dec. 24, 1940 UNITED STATES P'AITENDTIOFFICE MANUFACTURE F METALLIC I I RECEPTACLES Harold 'W. C lark,'Alliance, Ohio, assignor to The Steel Sanitary Company, Alliance, Ohio, a cor-I poration of Ohio 7 Original application November 7, 1935,. Serial No.

1-Claim. (01. 113-420) This invention relates to the manufacture of metal receptacles and, in particular, to receptacles made by the deep drawing of sheet steel. The invention will be disclosed as applied to the manufacture of bath tubs from sheet steel, but it will be apparent that other articles of like nature may be produced by the same method and apparatus, or with only slight modifications thereof. This application is a division of my copending application, Serial No. 48,664, filed November 7, 1935, now Patent No. 2,176,738, dated Oct. 17, 1939. Certain other subject matter disclosed in my said application SerialNo. 48,664 and in this application but not claimed in either thereof is disclosed and claimed in my copending applications Serial Nos. 260,576 and 260,577, filed of even date herewith, which are also divisions of my said copending application. Serial No. 48,664.

20 The manufacture of deep receptacles such as bath tubs, by welding sheet metal stampings or drawn blanks, presents numerous perplexing problems. It is found, for example, that after a blank has been drawn to form the drain end of 25 the tub, it is impossible to further deform the bottom of the blank preparatory to providing a drain-hole, without fracturing the metal. This condition constituted a serious obstacle to the successful manufacture of sheet steel tubs be- 3 cause the fractured blanks could not be reclaime but had necessarily to be scrapped.

I have invented a novel method of forming a drain-hole in the bottom of a receptacle made by a deep-drawing operation on a fiat sheet,

35 which overcomes the aforementioned objection to the procedure followed heretofore. In a preferred practice of the invention, I punch a hole in the bottom of the blank after the initial deepdrawing operation, at the point where the drain 40 opening is to be located, an thereafter deform the metal adjacent the hole to provide the desired depending neck. I thus avoid the formation of cracks in the metal adjacent the drainhole. The invention will be explained in detail herebelow by reference to the accompanying drawing illustrating one form of apparatus for forming blanks to constitute the drain end of a tub and the general appearance of the blanks for both the drain end and the other end of the tub, prior to their union by welding. In the draw? mg- Fig. 1 is an elevation of blanks drawn from sheet steel in condition for welding together to form a tub; and 55 Fig. 2 is a central section through an apparatus suitable for forming the blanks constituting the drainend of a tub. I

I prefer to employ a so-called toggle press for forming the tub sections. As is well known, this is a form of mechanical press having two slides or vertically movable members adapted to operate in a predetermined succession. Since the construction of presses of this character is well known, it is not herein illustrated nor described. It is sufiicient to state that the press has a work-supporting table in the form of a bolsteradapted to support the dies through which the sheet is drawn, and at least two vertically movable slides adapted to operate in succession.

A bottom spacer I0, which is a box-shapedlfi casting open at the top and bottom, is adapted to rest on the bolster. A draw ring I2 is secured to the bottom spacer I0. The draw ring is substantially U-shaped in outline, having an opening extending thereinto and rounded at the inner end, the edgeof the'opening being curved at the sides and rounded end thereof, as shown at l4. The upper surface of the draw ring I2 is provided with ribs, tongues or'splinesfl5 extending along the sides and rounded end of the opening I3. The purpose of these splines will become apparent as the description of theapparatus proceeds.

A pressure pad I6 is reciprocable within the bottom spacer III by means of pneumatic cylinders having piston rods I 8 slidable therein on which the pad rests. The supply of air to the cylinders is controlled by any suitable form of valve. The upper surface of the pad I6 is concave, to assist in shaping a metal sheet being drawn to the final contour desired in the finished product. The pad I6 is provided with a filler 44. The inner end of the punch, furthermore, is inclined as at 45. As a result, the inner end of the blank, as it is formed, is bent upwardly around the inclined end of the punch. This construction of the pad, filler and punch restrains flow of metal stock around the punch toward the closed end of the blank.

A blank holder ring 22 is mounted on one of the slides of the press, specifically that which descends first. The blank holder ring is simply a heavy plate or slab with an opening therein conforming generally to the outline of that in the draw ring I2. The blank holder ring is closed and the punch extension 26 is recessed at 4! to receive the inner cross member thereof. The undersurface of the blank holder ring has grooves 24 therein adapted to overlie the ribs or splines I5 on the draw ring I2. It will be apparent that 'pad 15 assists in giving-theproper form to the vfinishedtub section, being. depressed against the edges.

if a steel sheet is laid across the draw ring l2 while the blank holder ring 22 is elevated, the cooperating ribs or splines and grooves will serve to grip the edge of the plate, as in icated in Figuret2vand retard flow of the, metal, sheet therebetween as the centraliportion thereof is pressed inwardly and downwardly.

A punch 25 mounted on an extension 26secure to the other slide of the press, viz., that which descends last. The punch25 is-shaped to produce the desired contour of the finished tub section. i

The operation of theapparatuszalready described will probably be apparent but will nevertheless be reviewed briefly. ,The..togg1e press is first operated so as to withdrawthe punch .25 and the blank holder ring 1.22. ,A.-.steel,sheeti-is laid across the draw ring l2. The press is then operated so as to cause the blank holder ring 22 to descend and grip the sheet 30 adjacent its The'pad I6 is thenz raised to'meet the descending punch. The press :is :then :operated .so as to' cause the punche25to descend: and pro- 1 gressively shape thetsheet from the flat condition, .to: the final for-m shown in Figure .2. As-the punch descends and deforms theesheet, theedges and central portion thereof are stretchedand deforme and there isaetuallysomefiow of the edges of-the-sheet between the draw ring and-the stocka fiat sheet having theminimum dimensions sufilcientto form a tubsothatthe waste due to scrap-is correspondingly: reduced. At the same'time the centerportion of the blank is smoothly shaped to the desiredscontour. The

airzpressure in the cylinders I! by the punch 25 .as thelatter descends.

The .finished. tub section ,.has .the= appearance .shown .at 33:in Fignlpaftertheend of the section-is trimmeduoff andpthe edges of the section sheared and flanged upwardly was shown :The .method sand apparatus 1 above v described, with some slight :modification, may-also be. em-

material surrounding the hole before punching the hole itself.

mile'it is quite possible to form tub sections in aisinglerpressinggoperation as described above, I, have found .thatthe operation can be somewhatg'facilitated.,by. making it in two stages and .annealing the -.partly formed sections after the 1first-:.operation-atatemperature of between 1300 and 1400 F.

After the tub sections shown in Figure 1 have "been produced, they are'readyfor joining for example, by electric-welding, and, -after thew welded joint hasbeen ground down, thefinished tub can be annealed inthevusual'manner.

It will be apparent from the foregoing descriptionthat the invention-providesa simple and effective .method of providing a drain-hole in the bottom of e a deep-drawn receptacle, without the for-mation of the cracks which have vbeen encountered when followingthe rprocedurezknown heretofore. The method :adds nothing :to "the cost of operations andefiectsza greatisavingrin material which previously 'had :to be scrapped.

Although I haveillustratedzand described; but

. one preferred einbodimentszof the-aapparatus and practice ofthe methodgapparatus-and: procedure otherthan that 'descr-ibedmay .be employed without departing from the spirit. of ithe invention or the scope of the appended claim.

Iclaima A method for-making a-rblank for .a deep; receptacle having abottom and-a drain-holertherein, the:steps=including: subjecting a fiatwzmetal sheet to -a deep-drawing operation, thereby -ef- .fecting -a heavy Y cold-working by stretching of L the portion .of .the sheet. forming the :bottom' of theblank, .forming -:a,- hole: in .the bottom .of. the drawn ,blank, and-then,.pressi-ng'the metal radjacent-the hole out of, the general plane of the bottom to. provide adrain for the receptacle.

-HARQLD .W. CLARK. 

